The government last night faced pleas to deliver urgent help to home-buyers to revive the plunging property market as official data showed sales last month fell to their lowest levels for nearly 10 years.

As a Treasury-commissioned report warned that the credit crunch would continue to make it difficult for home buyers to obtain mortgages until 2010, industry experts were frustrated that Alistair Darling was waiting until his pre-budget report in the autumn to announce steps to ease conditions in the mortgage market.

The gloomy report commissioned by Darling from former HBOS chief executive Sir James Crosby warned that customers would have difficulties repaying their existing mortgages and that a lack of housing finance could have an impact on both house prices and consumer spending.

Crosby told the chancellor he was looking "with some urgency" at options for stimulating the supply of mortgages, which has seized up because of the credit crunch, including whether the government should guarantee new bonds containing packaged-up mortgages to try to stimulate financing for home loans.

The interim Crosby report was issued after official data demonstrated the scale of the slide in the mortgage industry. The Bank of England data showed a near-70% fall in house sales in June compared with the same month last year to the lowest level since 1999 when the data was first collected. Mortgage approvals fell to 36,000 in June from 41,000 in May and 114,000 a year ago.

Lenders, surveyors and house-builders united to call for swift intervention. John Stewart, director of economic affairs for the Home Builders Federation, said: "If the Treasury does not take up any recommendations from Crosby until the pre-budget report in October or November, this will unduly prolong the frustration of those, particularly first-time buyers, who are currently having difficulty obtaining mortgages to buy their own home.

"The benefits of action will not be realised until spring 2009 at the earliest - seven or eight months from now. This is too big a price to pay as in the meantime steeply falling housing transactions, weakening house prices and sharply lower housebuilding activity risk damaging Britain's wider economy."

There was more grim news from building societies, which said yesterday they were losing customers faster than they win new ones, resulting in negative net lending of £526m. This is the first time the sector has reported a negative figure since the Building Societies Association started studying the data 10 years ago.

Adrian Coles, director general of the BSA, preferred to focus on record inflows of savings, and said: "Many societies have chosen to follow a conservative lending policy to ensure that they maintain the high quality of their loan books."

Figures published by Abbey also appeared to indicate that the dynamics of the mortgage industry were changing. Abbey appears to have deposed Halifax from its position as the country's biggest lender by taking one in three of all mortgages between March and June. This 35% share of net lending compared with a share of about 9% last year.

Abbey predicted a fall in house prices of between 5% and 7% this year, while Halifax, which is owned by HBOS, is expecting a 9% fall. Nationwide building society is due to give its update on the housing market tomorrow, as is HBOS in publishing first-half profit figures.

Against this backdrop Crosby is considering whether there is a need for government intervention. He is not due to make any final recommendations before the autumn - more than a year after the credit crunch first started to bite - and conceded yesterday that he might suggest no intervention is needed at all.

Vince Cable, the Liberal Democrat Treasury spokesman, endorsed the latter course: "It is critical that siren voices in the City don't seduce ministers into using taxpayers' money to underwrite new banking and reinflate unsustainable house prices."

The Council of Mortgage Lenders made clear it expected action in the pre-budget report. Director general Michael Coogan said: "Without action the situation in the housing market will be worse than it needs to be. The housing correction will overshoot, and the knock-on effects on the wider economy will be significant."

Simon Rubinsohn, chief economist at the Royal Institution of Chartered Surveyors, said: "The latest numbers from the Bank of England demonstrate in the clearest possible way the consequences of the credit crunch for the residential property market. Unless the authorities take steps to restart the mortgage market the likelihood is that there will be more bad news in store for the both the housing market and retail sector during the latter part of the year."